Fungi and bacteria have been used to degrade polychlorinated biphenyl compounds (PCB's). The use of white-rot fungi, for example, to degrade PCB's is described by Aust and Tien, U.S. Pat. No. 4,891,320; Bumpus, J. A. et al. (1985) Science 228:1434-1436 and Eaton, D. C. (1985) Microbial Technology 7:194-196. These bioremedial processes have significant limitations and generally, they have not been used commercially. Fungal degradation of PCB's has been demonstrated only in small volumes of defined laboratory media with very low concentrations of polychlorinated biphenyl compound (100 to 1000 times less than typical concentration encountered in the field).
Bacterial processes have been limited by the selective degradation of congeners of PCB's. Although significant levels of PCB's can be degraded with bacteria, certain congeners usually are left undegraded. As a result, it would be difficult to achieve EPA mandated clean-up levels which, under the Toxic Substance Control Act (TSCA), currently allow a maximum of 10 ppm total concentration with no congener greater than 2 ppm. In addition, bacterial degradation proceeds rather slowly in field trials. Improved processes for degradation of polyhalogenated biphenyl compounds are needed.